From the Italian Patent Application No. 3376 A/87 (corresponding to U.S. application Ser. No. 07/154,782 filed concurrently herewith), an automatic machine is known for the continuous production of dual-use filter sachets for infusion products with successive bags or pouches containing fractional doses of such products.
The machine has an operating line provided with a succession of means designed to effect the following steps:
the folding and longitudinal sealing of a strip of thermally weldable filter paper in a horizontally oriented flattened tubular form,
thermally welding the tubes in a transverse direction to said tube so as to enclose single fractional doses fed thereto between two transverse thermal welds,
application by rotary wheel means with pickup elements of equidistantly spaced labels, a longitudinally continuous thread transversely contacting said labels as well as stickers or tabs of thermally weldable material partly adhered to the backs of the labels, to the flattened tube at alternate transverse thermal welds; and
cutting up the tube thus conformed into portions comprising at least two bags, for setting up these bags side by side and for sealing together their extremities.
More particularly, such a dual-use filter-paper sachet with multiple successive or serial bags or pouches each of which contains a corresponding fractional dose or unit quantity of the infusion product, has a structure allowing two modes of use, or in the flattened form collated in lots for sale with the bags or pouches in superimposed or serially stacked arrangement by folding back one bag or pouch over the other or adjacently thereto, and one with an unfolded or extended arrangement of the pouches following an action of pressing and pulling of the corresponding label covering the handling thread of the filter sachet by the user.
The thread has a length substantially equal to the length of the sachet in its arrangement for use in the unfolded mode of bags or pouches, and is fastened to the opposite extremity of said sachet by means of a sticker or tab of thermally weldable material together with the label which is made of a material which is not thermally weldable and arranged to surround longitudinally the exterior of the sachet when said bags or pouches are in the collated position in lots for sale in which the bags are folded back to back.